This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
ACCSautonomous component carrier selection3GPPthird generation partnership projectBSbase stationBWbandwidthCCcomponent carrierCSGclosed subscriber groupDLdownlink (eNB towards UE)ECescape carriereNBE-UTRAN Node B (evolved Node B)EPCevolved packet coreE-UTRANevolved UTRAN (LTE)HeNBhome eNBHOhandoverHSPAhigh speed packet accessIMTAinternational mobile telecommunications associationLTElong term evolution of UTRAN (E-UTRAN)LTE-ALTE advancedMACmedium access control (layer 2, L2)MM/MMEmobility management/mobility management entityNodeBbase stationOFDMAorthogonal frequency division multiple accessOAMoperations and maintenancePDCPpacket data convergence protocolPHYphysical (layer 1, L1)RelreleaseRLCradio link controlRLFradio link failureRRCradio resource controlRRMradio resource managementRSRPreference signal received powerSC-FDMAsingle carrier, frequency division multiple accessSGWserving gatewaySINRsignal to interference plus noise ratioUEuser equipment, such as a mobile station, mobile node or mobile terminalULuplink (UE towards eNB)UMTSuniversal mobile telecommunications systemUTRANuniversal terrestrial radio access networkWAwide areaWAeNBwide area eNB
One modern communication system is known as evolved UTRAN (E-UTRAN, also referred to as UTRAN-LTE or as E-UTRA). The DL access technique is OFDMA, and the UL access technique is SC-FDMA.
One specification of interest is 3GPP TS 36.300, V8.11.0 (2009-12), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (EUTRAN); Overall description; Stage 2 (Release 8),” incorporated by reference herein in its entirety. This system may be referred to for convenience as LTE Rel-8. In general, the set of specifications given generally as 3GPP TS 36.xyz (e.g., 36.211, 36.311, 36.312, etc.) may be seen as describing the Release 8 LTE system. More recently, Release 9 versions of at least some of these specifications have been published including 3GPP TS 36.300, V9.1.0 (2009-9).
FIG. 1A reproduces FIG. 4.1 of 3GPP TS 36.300 V8.11.0, and shows the overall architecture of the EUTRAN system (Rel-8). The E-UTRAN system 2 includes eNBs, providing the E-UTRAN user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UE (not shown). The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME by means of a S1 MME interface and to an S-GW by means of a S1 interface (MME/S-GW 4). The S1 interface supports a many-to-many relationship between MMEs/S-GWs and eNBs.
The eNB hosts the following functions:    functions for RRM: RRC, Radio Admission Control, Connection Mobility Control,    Dynamic allocation of resources to UEs in both UL and DL (scheduling);    IP header compression and encryption of the user data stream;    selection of a MME at UE attachment;    routing of User Plane data towards the EPC (MME/S-GW);    scheduling and transmission of paging messages (originated from the MME);    scheduling and transmission of broadcast information (originated from the MME or OAM); and    a measurement and measurement reporting configuration for mobility and scheduling.
Also of interest herein are the further releases of 3GPP LTE (e.g., LTE Rel-10) targeted towards future IMTA systems, referred to herein for convenience simply as LTE-Advanced (LTE-A). Reference in this regard may be made to 3GPP TR 36.913, V9.0.0 (2009-12), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for Further Advancements for EUTRA (LTE-Advanced) (Release 9), incorporated by reference herein. A goal of LTE-A is to provide significantly enhanced services by means of higher data rates and lower latency with reduced cost. LTE-A is directed toward extending and optimizing the 3GPP LTE Rel-8 radio access technologies to provide higher data rates at lower cost. LTE-A will be a more optimized radio system fulfilling the ITU-R requirements for IMT-Advanced while keeping the backward compatibility with LTE Rel-8.
As is specified in 3GPP TR 36.913, LTE-A should operate in spectrum allocations of different sizes, including wider spectrum allocations than those of LTE Rel-8 (e.g., up to 100 MHz) to achieve the peak data rate of 100 Mbit/s for high mobility and 1 Gbit/s for low mobility. It has been agreed that carrier aggregation is to be considered for LTE-A in order to support bandwidths larger than 20 MHz. Carrier aggregation, where two or more component carriers (CCs) are aggregated, is considered for LTE-A in order to support transmission bandwidths larger than 20 MHz. The carrier aggregation could be contiguous or non-contiguous. This technique, as a bandwidth extension, can provide significant gains in terms of peak data rate and cell throughput as compared to non-aggregated operation as in LTE Rel-8.
A terminal may simultaneously receive one or multiple component carriers depending on its capabilities. A LTE-A terminal with reception capability beyond 20 MHz can simultaneously receive transmissions on multiple component carriers. A LTE Rel-8 terminal can receive transmissions on a single component carrier only, provided that the structure of the component carrier follows the Rel-8 specifications. Moreover, it is required that LTE-A should be backwards compatible with Rel-8 LTE in the sense that a Rel-8 LTE terminal should be operable in the LTE-A system, and that a LTE-A terminal should be operable in a Rel-8 LTE system.
FIG. 1B shows an example of the carrier aggregation, where M Rel-8 component carriers are combined together to form M×Rel-8 BW (e.g. 5×20 MHz=100 MHz given M=5). Rel-8 terminals receive/transmit on one component carrier, whereas LTE-A terminals may receive/transmit on multiple component carriers simultaneously to achieve higher (wider) bandwidths.
So-called femto stations are a base station class having a lower maximum transmit power (and smaller cell area) as compared to a typical macro cell BS, such as an LTE or LTE-A eNB, also referred to herein as a WAeNB. Femto stations are typically designed for indoor deployments, such as in private residences or public areas, including office environments. Such femto BSs may be referred to for convenience as a home eNB (HeNB), although their use is not restricted to a home or residence. As the femto stations are intended to be deployed and maintained individually by customers, their geographical location cannot be assumed as being known to the operator of the macro cell BSs. Furthermore, as the number of femto cells within a given macro cell area can potentially be large, the optimum configuration of HeNB parameters from a centralized OAM function can be difficult to accomplish in practice.